Comparative Study on Shelf Life of Whole Milk Processed by High-Intensity Pulsed Electric Field or Heat Treatment I Odriozola-Serrano, S Bendicho-Porta, and O Martı´n-Belloso1 Department of Food Technology UTPV-CeRTA, University of Lleida Rovira Roure 191, 25198 Lleida, Spain ABSTRACT The effect of high-intensity pulsed electric fields (HIPEF) processing (35.5 kV/cm for 1,000 or 300 ␮s with bipolar 7-␮s pulses at 111 Hz; the temperature outside the chamber was always βLG > serum albumin Regarding the destruction of whey protein during storage, untreated and HIPEF-treated (for 300 ␮s) milk had faster protein destruction than thermal and HIPEF (for 1,000 ␮s) treatments These results could be attributed to an increase in proteolytic activity produced by the microflora of milk Bendicho et al (2003a) observed that proteolytic activity increased or decreased significantly depending on the applied HIPEF treatment when the medium was skim milk Protease activity decreased with increased treatment time, field strength, or pulse rate The maximum inactivation (81%) was attained in skim milk at 35.5 kV/cm and 111 Hz for 866 ␮s CONCLUSIONS High-intensity pulsed electric field processing (35.5 kV/cm for 1,000 ␮s with 7-␮s bipolar pulses at 111 Hz) can produce stable whole milk with a shelf life comparable to that of heat-pasteurized milk (75°C for 15 s) Treating whole milk with HIPEF was as effective as heat pasteurization in terms of microorganisms, enzyme, and physical stability However, HIPEF (300 ␮s) treatment did not have important effects on the studied parameters Treatment by HIPEF for 1,000 ␮s extended the shelf life of whole milk to d, a similar result to that achieved with traditional pasteurization ACKNOWLEDGMENTS The authors thank the Interministerial Comission for Science and Technology (CICYT) of Spain for their support of the work included in the Project ALI 97 0774, and also thank the Age`ncia de Gestio´ d’Ajuts Universitaris i de Recerca of the Generalitat 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Effects of high-intensity pulsed electric field (HIPEF) treatment and heat pasteurization on total aerobic bacteria of whole milk throughout storage at 4°C Type of milk treatment: untreated (छ), heat. .. microorganisms by absorbing free radicals and ions, which are active in the cell breakdown (Gilliland and Speck, 1967) Effect of Processing and Storage Conditions on pH and Acidity Values of pH and acidity